1. Field of the Invention
This invention relates to a relay, more particularly to a single-pole magnetic reed relay which has an improved construction that utilizes a fewer number of elements and simpler steps to form the single-pole magnetic reed relay.
2. Description of the Related Art
Generally speaking, there are three different types of conventional magnetic reed relays. The first type of a magnetic reed relay is a single-pole magnetic reed relay which has a row of terminals formed on the bottom surface of a case thereof. The second type of a magnetic reed relay is a dual-pole magnetic reed relay which has two rows of terminals formed on the bottom surface of a case thereof. The third type of a magnetic reed relay is an IC magnetic reed relay which can be mounted directly on a printed circuit board.
The improvement of this invention is directed to a conventional single-pole magnetic reed relay, as shown in FIG. 1, which includes a coil reel 1, a pair of transmission terminals 2, a coil 3, a reed contact unit 4, a printed circuit board 5, a pair of coil terminals 6, and a case 7.
The coil reel 1 is formed integrally from a plastic material and includes an axially extending reel portion (1a) which has an axially extending hole (1a1) formed therethrough. A stop wall (1b) is formed on one end portion of the reel portion (1a) and has the axially extending hole (1a1) extending therethrough. A pair of extension blocks (1c) are formed on the other end portion of the reel portion (1a). The extension blocks (1c) are spaced apart from each other to confine a radially extending groove (1c1) therebetween. The radially extending groove (1c1) is communicated with the axially extending hole (1a1) of the reel portion (1a). Each of the extension blocks (1c) has a radially extending hole (1c2) formed therethrough.
The transmission terminals 2 extend respectively through the radially extending holes (1c2) of the extension blocks (1c) and have head portions (2a) positioned respectively on the top surfaces of the extension blocks (1c), as shown in FIG. 2.
The coil 3 is wound around the reel portion (1a) and has two end portions (3a) connected respectively and electrically to the head portions (2a) of the transmission terminals 2.
The reed contact unit 4, as shown in FIG. 1, can extend through the axially extending hole (1a1) of the reel portion (1a) and has an insulated tube (4a), which is disposed within the axially extending hole (1a1), and two conducting end portions (4b, 4c) which extend from two ends of the insulated tube (4a) respectively through the stop wall (1b) and through the radially extending groove (1c1).
The printed circuit board 5 supports the coil reel 1 thereon (see FIG. 2) and has two first holes (5a) formed therethrough and aligned respectively with the radially extending holes (1c2) of the extension blocks (1c) for allowing the transmission terminals 2 to extend therethrough. The transmission terminals 2 are welded within the first holes (5a), while the rest of the transmission terminals 2 which protrude outwardly of the printed circuit board 5 are cut off. The printed circuit board 5 further has two second holes (5b) formed therethrough at two end portions thereof for allowing the conducting end portion (4b, 4c) of the reed contact unit 4 to extend therethrough, and two third holes (5c) formed therethrough and located between the second holes (5b). The second and third holes (5b, 5c) are aligned with and are spaced apart from one another at equal distances. The printed circuit board 5 further has conducting elements (not shown), such as a copper coating, formed thereon and extending from each of the second holes (5b) to a respective one of the third holes (5c).
Each of the coil terminals 6 has a positioning portion (6a) welded within a respective one of the third holes (5c) of the printed circuit board 5. The coil terminals 6 and the conducting end portions (4c, 4b) of the reed contact unit 4 are therefore aligned with one another to constitute the first type of single-pole magnetic reed relay, as shown in FIG. 2. Owing to the presence of the transmission terminals 2 and the conducting elements on the printed circuit board, the coil 3 can be connected electrically and indirectly to the coil terminals 6.
The case 7 is used to contain the coil reel 1, the transmission terminals 2, the coil 3, the reed contact unit 4, the printed circuit board 5, and the coil terminals 6. Then, a resin is provided in the case 7 to encapsulate the coil reed 1, the transmission terminals 2, the coil 3, the reed contact unit 4, the printed circuit board 5, and the coil terminals 6 in the case 7 while allowing only sections of the conducting end portions (4b, 4c) of the reed contact unit 4 and the coil terminals 6 to extend outwardly of the case 7. Finally, the sections of the conducting end portions (4b, 4c) of the reed contact unit 4 and the coil terminals 6 are trimmed so as to be equal in length, thereby forming the conventional single-pole magnetic reed relay.
Because of the indirect electrical connection between the coil 3 and the coil terminals 6 via the transmission terminals 2 and the conducting elements on the printed circuit board, the conventional single-pole magnetic reed relay has to be tested after manufacture to ensure whether or not there is electrical connection between the coil 3 and the coil terminals 6. In addition, because the conventional single-pole magnetic reed relay requires a considerable number of parts as described above, it is not easy to combine these parts to constitute the conventional single-pole magnetic reed relay. Owing to the complicated combination of the parts of the conventional single-pole magnetic reed relay, the conventional single-pole magnetic reed relay has a relatively high manufacturing cost.